With Machine-to-Machine (M2M) communication being more and more deployed in cellular networks, problems with how to address the M2M devices (user equipment; UE's) for Mobile Terminated Communication from M2M application servers arise. With the use of dynamic IP address assignments, a mechanism where the M2M application server gets to know the IP address of the device needs to be present. In some applications the device/UE itself can contact the M2M application server and inform about its presence and IP address, but in other applications the communication needs to be initiated from the M2M application server side, where the application server may not know the IP address of the device.
Another problem with the growing interest in M2M cellular communications is that each device/UE today is assigned an E.164 Mobile Subscriber Integrated Services Digital Network (MSISDN) number. With the expected growth of M2M devices being 50 Billion and beyond, these identities will soon be exhausted. This has been pointed out by the International Telecommunications Union (ITU) which has asked 3GPP to find new solutions for addressing mobile devices. It is even suggested that the E.164 MSISDN shall not be mandatory for M2M devices anymore, as these numbers are mainly targeted for human communication.